Dust-protective cycling lubricating structure of an electric fan

ABSTRACT

An dust-protective cycling lubricating structure of an electric fan is disclosed to include a hub defining a receiving chamber, a shaft rotatably mounted in the hub, an axle bearing mounted in the receiving chamber to support the shaft and defining with a top cover of the hub an oil-spreading space and a bottom cover of the hub an oil accumulation space. Lubricating oil is guided upwards by guide grooves on the shaft to lubricate the shaft and the axle bearing and to be further spread over the oil-spreading space and then returned to the oil accumulation space due to the effect of the centrifugal force during rotation of the shaft with a fan blade assembly.

This application claims the priority benefit of Taiwan patent application number 094210028 filed on Jun. 15, 2005.

BACKGROUND OF THE INVENTION

1. Field of the Invention:

The present invention relates to an electric fan and more specifically, to a dust-protective cycling lubricating structure of an electric fan, which maintains smooth circulation of lubricating oil to effectively lubricate the shaft and the axle bearings of the electric fan, and eliminates leakage of lubricating oil.

2. Description of the Related Art:

Following fast development of computer technology, high-speed CPUs (Central Processing Units) have been continuously created. These high-speed CPUs produce much heat during operation. In order to maintain normal operation of a CPU, heat must be quickly carried away from the CPU. Various cooling fans have been developed for this purpose. A cooling fan uses axle bearings to support the shaft so that the shaft can be rotated with the fan blade assembly at a high speed. The use of axle bearings in a cooling fan is adapted to achieve the objects of prolonging the work life of the electric fan and reducing the noise level and loss of power of the electric fan. In order to achieve these objects, the axle bearing and shaft of a cooling fan must be well lubricated to lower the friction. Therefore, the gap between the axle bearing and the shaft in a cooling fan is generally filled with lubricating oil. FIG. 5 shows the lubricating structure of a conventional cooling fan. As illustrated in FIG. 5, the fan shaft A has oil guide grooves A1 on the periphery, and is supported on an axle bearing B in a center hole C1 of a socket C. During rotation of the fan shaft A, the oil guide grooves A1 suck lubricating oil from an oil trough C2 to lubricate the axle bearing B. This lubricating structure has numerous drawbacks as outlined hereinafter:

1. The oil trough C2 is formed in the socket C at the bottom side.

When the cooling fan is kept in vertical, lubricating oil is accumulated in the oil trough C2. At this time, the centrifugal force that is produced during rotation of the fan shaft A is insufficient to draw lubricating oil upwards from the oil trough C2 to the gap between the fan shaft A and the axle bearing B.

2. Because the oil trough C2 is provided at the bottom side inside the socket C and the oil guide grooves A1 of the fan shaft A are disposed in the center area of the axle bearing B, the oil guide grooves A1 cannot effectively guide lubricating oil upwards from the oil trough C2 to the gap between the axle bearing B and the fan shaft A during rotation of the fan shaft A.

3. The top side of the socket C is an open side. When the cooling fan is placed in horizontal during packing, delivery or an use, lubricating oil may flow from the oil trough C2 through the gap between the fan shaft A and the axle bearing B to the outside of the socket C. During operation of the cooling fan, lubricating oil may also be forced out of the socket C by the produced centrifugal force. Further, external dust and impurities may fall to the inside of the socket C to contaminate lubricating oil, and oil dirt may be accumulated in the gap between the fan shaft A and the axle bearing B, thereby increasing friction between the fan shaft A and the axle bearing B during rotation of the fan shaft A and shortening the work life of the cooling fan.

SUMMARY OF THE INVENTION

The present invention has been accomplished under the circumstances in view. According to one aspect of the present invention, the dust-protective cycling lubricating structure is used in an electric fan, comprising a hub, which has a center barrel covered with a top cover and a bottom cover and a receiving chamber defined in the center barrel between the top and bottom covers, a shaft, which is rotatably mounted in the center barrel of the hub, and an axle bearing, which is mounted in the receiving chamber to support the shaft in the center barrel. The axle bearing defines with the top cover an oil-spreading space in the top side of the receiving chamber. The axle bearing also defines with the bottom cover an oil accumulation space in the bottom side of the receiving chamber. Lubricating oil is guided upwards by guide grooves on the shaft to lubricate the shaft and the axle bearing and to be further spread over the oil-spreading space and then returned to the oil accumulation space due to the effect of the centrifugal force during rotation of the shaft with a fan blade assembly.

According to another aspect of the present invention, an elastic porous oil retainer is mounted in the oil accumulation space around the shaft to retain lubricating oil for circulation in the receiving chamber and to filtrate dust and impurities from lubricating oil.

According to still another aspect of the present invention, solidified oil is filled up gaps between the center through holes of the top and bottom covers and the periphery of the shaft to stop lubricating oil from flowing out of the receiving chamber and to prohibit outside dust and impurities from entering the receiving chamber.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exploded view of a dust-protective cycling lubricating structure of an electric fan in accordance with a first embodiment of the present invention.

FIG. 2 is a cutaway view of the first embodiment of the present invention.

FIG. 3 is sectional side view of the first embodiment of the present invention.

FIG. 3A is an enlarged view of a part of FIG. 3.

FIG. 4 is sectional side view of a dust-protective cycling lubricating structure of an electric fan in accordance with a second embodiment of the present invention.

FIG. 4A is an enlarged view of a part of FIG. 4.

FIG. 5 is a sectional side view of the lubricating structure of a conventional cooling fan.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to FIGS. 1, 2, 3 and 3A, a dust-protective cycling lubricating structure of an electric fan in accordance with the present invention is shown comprised of a hub 1 and a shaft 2.

The hub 1 has an axially extending center barrel 11, which defines a receiving chamber 110, a top cover 12, which is covered on the top side of the receiving chamber 110 and has a center through hole 121 in communication with the receiving chamber 110, and a bottom cover 13, which is covered on the bottom side of the receiving chamber 110 and has a center through hole 131 in communication with the receiving chamber 110. Two axle bearings 14 are arranged in a stack inside the receiving chamber 110, defining with the bottom wall of the top cover 12 an oil-spreading space 16. The axle bearings 14 each has a center axle hole 141 disposed in line with the center through hole 121 of the top cover 12 and the center through hole 131 of the bottom cover 13. Further, the axle bearings 14 preferably have a porous structure. Further, longitudinal oil grooves 15 are formed between the axle bearings 14 and the center barrel 11 of the hub 1. The longitudinal oil grooves 15 can be on the periphery of each of the axle bearing 14 or the inside wall of the center barrel 11 of the hub 1. Flow guide ribs 161 are formed integral with the bottom wall of the top cover 12 and suspending in the oil-spreading space 16. Further, an oil accumulation space 17 is defined in the receiving chamber 110 between the bottom side of the axle bearings 14 and the top wall of the bottom cover 13.

The shaft 2 is mounted in the receiving chamber 110 of the center barrel 11 of the hub 1, having guide grooves 21 formed on the periphery and disposed between the axle bearings 14 and the oil accumulation space 17 and a locating groove 22 extending around the periphery near one end, namely, the bottom end thereof. A retaining ring 221 is fastened to the locating groove 22 of the shaft 2 to secure the shaft 2 to the hub 1, allowing rotation of the shaft 2 relative to the hub 1. A fan blade assembly 23 is fixedly mounted on the other end, namely, the top end of the shaft 2 outside the center barrel 11 of the hub 1.

Referring to FIGS. 3 and 3A again, during assembly process of the present invention, the axle bearings 14 are inserted in proper order into the receiving chamber 110 of the center barrel 11, and then the shaft 2 is inserted in proper order through the center through hole 121 of the top cover 12, the center axle holes 141 of the axle bearings 14 and the center through hole 131 of the bottom cover 13, and then the retaining ring 221 is fastened to the locating groove 22 of the shaft 2 to secure the shaft 2 in place. After installation of the present invention, lubricating oil is filled in the receiving chamber 110 of the center barrel 11 of the hub 1, for enabling lubricating oil to be accumulated in the oil accumulation space 17. During rotation of the shaft 2 with the fan blade assembly 23, the capillary structure of the guide grooves 21 of the shaft 2 causes a siphon action to suck lubricating oil from the oil accumulation space 17 to the guide grooves 21 for lubricating the shaft 2 and the axle bearings 14 and also to guide sucked lubricating oil toward the top side for enabling lubricating oil to be further thrown away from the shaft 2 by the centrifugal force produced during rotation of the shaft 2 into the oil-spreading space 16 and guided by the flow guide ribs 161 to the longitudinal oil grooves 15 between the center barrel 11 and the axle bearing 14 and then returned to the oil accumulation space 17 for further circulation. Therefore, lubricating oil is continuously circulated in the receiving chamber 110 inside the center barrel 11 of the hub 1 to lubricate the related parts.

FIGS. 4 and 4A show an alternate form of the present invention. According to this embodiment, an elastic porous oil retainer 18 is mounted in the oil accumulation space 17 inside the receiving chamber 110 of the center barrel 11 of the hub 1 to retain lubricating oil. The elastic porous oil retainer 18 is preferably made out of sponge, having a through hole 181. When lubricating oil is returned to the oil accumulation space 17, the elastic porous oil retainer 18 filtrates dust and impurities from lubricating oil, for enabling clean lubrication oil to be further circulated in the receiving chamber 110.

Further, solidified oil may be filled in gaps between the center through holes 121 and 131 of the top and bottom covers 12 and 13 and the periphery of the shaft 2. Thus, lubricating oil is prohibited from flowing out of the receiving chamber 110 and outside dust and other solid matters are prohibited from entering the receiving chamber 110 when the hub 1 is placed in horizontal or turned upside down. Therefore, lubricating oil in the receiving chamber 110 is constantly kept clean for lubrication.

As indicated above, the dust-protective cycling lubricating structure of the present invention has the following benefits:

1. The guide grooves 21 of the shaft 2 are disposed between the oil accumulation space 17 and the axle holes 141 of the axle bearings 14 so that the siphon action of the capillary structure of the guide grooves 21 of the shaft 2 sucks lubricating oil into the gaps between the shaft 2 and the axle bearings 14 to lubricate the shaft 2 and the axle bearings 14 effectively.

2. The centrifugal force produced during rotation of the shaft 2 causes lubricating oil to be thrown away from the shaft 2 into the oil-spreading space 16 and then guided by the flow guide ribs 161 to the longitudinal oil grooves 15 and then returned to the oil accumulation space 17 for further circulation.

3. The elastic porous oil retainer 18 is installed in the oil accumulation space 17 to retain lubricating oil so that when the shaft 2 is rotating, the elastic porous oil retainer 18 is forced by the centrifugal force to release lubricating oil for lubricating the shaft 2 and the axle bearings 14 so as to prolong the work life of the electric fan.

4. The elastic porous oil retainer 18 is installed in the oil accumulation space 17 to retain lubricating oil so that lubricating oil does not flow out of the hub 1 through the center through hole 121 of the top cover 12 when the electric fan is placed in horizontal or turned upside down.

5. Solidified oil may be filled in gaps between the center through holes 121 and 131 of the top and bottom covers 12 and 13 and the periphery of the shaft 2, so that lubricating oil is stopped from flowing out of the receiving chamber 110 of the hub 1 and outside dust and solid matters are prohibited from entering the receiving chamber 110 of the hub 1 when the electric fan is placed in horizontal or turned upside down. Therefore, the shaft 2 and the axle bearings 14 are constantly lubricated, preventing vibration of the shaft 2 during operation of the electric fan and contamination of lubricating oil with dust.

A prototype of dust-protective cycling lubricating structure of an electric fan has been constructed with the features of FIGS. 1˜4. The dust-protective cycling lubricating structure of an electric fan functions smoothly to provide all of the features disclosed earlier.

Although particular embodiments of the invention have been described in detail for purposes of illustration, various modifications and enhancements may be made without departing from the spirit and scope of the invention. Accordingly, the invention is not to be limited except as by the appended claims. 

1. A dust-protective cycling lubricating structure comprising: a hub, said hub comprising an axially extending center barrel, said center barrel defining a receiving chamber, a top cover covered on a top side of said receiving chamber, and a bottom cover covered on a bottom side of said receiving chamber; a shaft inserted through said center barrel, said top cover and said bottom cover and rotatable relative to said hub; at least one axle bearing mounted in said receiving chamber of said center barrel around said shaft to support said shaft in said center barrel, said at least one axle bearing each having a center axle hole for the passing of said shaft and a plurality of longitudinal oil grooves formed between said axle bearings and said center barrel of said hub, said at least one axle bearing defining with said top cover an oil-spreading space in a top side of said receiving chamber and defining with said bottom cover an oil accumulation space in a bottom side of said receiving chamber.
 2. The dust-protective cycling lubricating structure as claimed in claim 1, further comprising a plurality of flow guide ribs suspending in said oil-spreading space.
 3. The dust-protective cycling lubricating structure as claimed in claim 1, wherein said shaft has at least one guide groove on the periphery thereof between said axle bearings and said oil accumulation space for sucking lubricating oil upwards from said oil accumulation space upon rotation of said shaft.
 4. The dust-protective cycling lubricating structure as claimed in claim 1, wherein said shaft has a top end extending out of said top cover and mounted with a fan blade assembly and a bottom end extending out of said bottom cover, said bottom end of said shaft having a locating groove extending around the periphery thereof and a retaining ring fastened to said locating groove to secure said shaft to said center barrel.
 5. The dust-protective cycling lubricating structure as claimed in claim 1, wherein said top cover is formed integral with a top side of said center barrel.
 6. The dust-protective cycling lubricating structure as claimed in claim 1, wherein said bottom cover is formed integral with a bottom side of said center barrel.
 7. The dust-protective cycling lubricating structure as claimed in claim 1, further comprising a solidified oil filled up gaps between the center through holes of said top and bottom covers and the periphery of said shaft.
 8. The dust-protective cycling lubricating structure as claimed in claim 1, wherein said at least one axle bearing each has a porous structure.
 9. The dust-protective cycling lubricating structure as claimed in claim 1, further comprising an elastic porous oil retainer mounted in said oil accumulation space inside said center barrel around said shaft for retaining lubricating oil, said elastic porous oil retainer made out of sponge having a through hole.
 10. The dust-protective cycling lubricating structure as claimed in claim 1, wherein said longitudinal oil grooves can be on the periphery of each of said axle bearing.
 11. The dust-protective cycling lubricating structure as claimed in claim 1, wherein said longitudinal oil grooves can be on the inside wall of said center barrel of said hub. 